donkin



3 Sheets Sheet 1.

(No Model.)

E. B. DONKIN.

y RQTARY PUMP.

lPatented May 20, 1884.

NA PETERS. Pnumuxnogmpmr. wmingmn. D4 C.

(No Modl.) 3 Sheets-Sheet 2,

E.` B. DONKIN.

ROTARY PUMP.

No. 298.952. 4Patented May 20, 1.884.

HEI

N. PETERS, Fhom-Limogrnpher, wnnhlngmn. D. c.

(No Model.) Y 3 Sheets-Sheet 3.1

E. B. DONKIN.

i ROTARY PUMP. No. 298,952. Patented May 20, 1884.

EDWIN BRYAN DON KIN, OF BERMONDSEY, ENGLAND.

ROTARY PU IVI P.

SPECIFICATION forming part of Letters Patent No. 298,952, dated May 20, 1884.

Application filed August 13, 1883.

(No model.) Patented in England January 13, 1883,190. 216; in France July 12, 1883, No. 156,519;

in Belgium July i6, i883, No. 62,135, and in Germany July ill), 1883.

To lf/ZZ wiz/0712, it may concern:

Be it known that I, EDWIN BRYAN DoNKrN, a subject of the Queen of Great Britain, residing at Southwark, Park Boad, Bermondsey, England, have invented certain new and use ful Improvements in Rotary Pumps and Eugines, (for which I have received Letters Patent in Great Britain, No. 216, dated January 18, 1883; in France, N o. 156,519, dated July l2, 1883; in Belgium, No. 62,135, dated July 26, 1883, and in Germany, dated July 29,1883,) of which the following is a specification.

This invention has for its object to improve that class of rotary pumps or engines, in which a piston is carried by the pin of a crank made to revolve in a casing of a form approaching somewhat to the cardioidal form. By my improvements I am able to construct such pumps or engines with larger inlet and outlet ports than heretofore, and am also able to better control the movement of the piston.

In the drawings hereunto annexed I have shown examples of pumps or engines constructed according to my invention.

Figure l is a transverse section, and Fig. 2 a longitudinal section, of one form of the pump or engine. Figs. 3 and 4. are similar views of a modified form of this pump or engine, and Figs. 5 and 6 are similar views of another form, and Fig. 7 a transverse section of another modiiication. Figs. 8, 9, and l0 show the piston and guides in several successive po sitions. Figs. 1l, l2, and 13 show details of the piston and guides in the double arrangement represented by Fig. 7

In Figs. 1 and 2, A is the casing or cylinder. Its inner surface is in transverse section, approXimately, a cardioid curve-that is, a curve along which any point upon a circle is car ried when that circle is caused to roll around a second stationary circle of equal diameter. B is an oblong piston, through the center of which passes a cranklpin, O, carried by an axis, D, the center of which would coincide with the center of the stationary circle above mentioned. The radial distance between the central line of the axis D, and the centralline ofthe crank-pin is made somewhat less than the radius of the above-mentioned circle, and

the extreme point of the inward bend of the cardioid curve is also cut ofi", as shown, so that the piston B may at the center be of sufiicicnt thickness to give it the requisite strength. As the piston is carried round by the crank it is caused to make ahalf-revolution for each complete revolution ofthe crank-axis. rIhe ends of the piston are made to fit closely up to the ends of the casing, and the curve of the casing is such that the edge of the piston which isat any time farthest 'from the inward bend of the casing always fits up to the side of the casing in whatever position the crank may be. Vhen the piston is in the position shown at Fig. 1, it is at right angles to a line radial to the axis which passes through the center of the crank-pin, and the extremity of the `inward bend,A of the casing is made to iit up to the center 'of the top side of the piston. The piston is made to taper from its center to its two side edges, and theinward bend of the casing is so shaped that when the crank-axis is revolved and the piston carried round by the crankarm, one side of this portion A of the casing always fits against one side of the piston until the piston comes into a position at right angles to that in which it is shown. The inward bend of the casing then fits to the edge of the piston. A still further movement of the pistou brings its opposite side into contact with the other side of this portion AX of the casing, and so the piston is carried round continuously,making, as before stated half arevelution for each complete revolution of the crankshaft.

E is an inlet-port for admitting air or other iiuid to thel casing, and F the outlet-port by which it is expelled from the casing. Theinward bend of the casing separates these two ports, and,always fitting to the piston, as above described, prevents the passage of fluid directly from one to the other. It will be seen that by making the casing to bend inward in the manner shown, and always llit to the piston at this point, that ports of very large size may be made use of, whereas if the casing did not at this point fit to the piston the size of ports whichcould be used would be very restricted.

boss, from which project rods I.

. the other as they revolve the blocks are at In order to 'control the movement of the piston as `vit is carried round by the crank-pin, so asto 'keep its ends always close to the sides of the casing without rubbing against them, I control the movements of the piston in the following manner: The crank-pin C is made to project from a disk, G, on the axis D. This disk is received in a recess at one end of the casing A. The other end of the crank-pin passes through a disk, H, which is concentric with the crank-axis, and which is free to re- *volve in a corresponding hole in the opposite end of the casing. A tubular neck projecting from the end ofthe piston also passes through this disk. Outside the disk it has upon it a These at their ends have projections J, extending from them parallel with the crank-pin, and these carry pairs'of, parallel guide-bars K, in the form of a right-angled cross. One pair of guide-bars is parallel with the piston, and the other at right angles to it. Between each pair of guide-bars is an oblong block, L, turning on a pin, M, carried by a casing, A, fixed to the end of the casing A. rIhe pins M are on opposite sides of and equidistant from the crank-axis. A` radial line drawn through the extremity of the inward bend of the cardioid curve passes through the center of one pin.

The other is on the opposite side of the crankaxis. Both of them are at the same distance from the axis as the crank-pin that carries the piston. The two pins M are connected by a bar, N. The crank-pin has at its end an arm,

GX, carrying a pin which is concentric with the `crank-axis, and this pin is received in a bearing formed to receive it in the center of the bar N. As the piston is carried round by the crank-pin, the blocksLare turned on the pinsM, each making a half-turn for every complete revolution of the crank; and in order that the ends ofthe blocks may not strike one against their ends cut away on one side, so as to reduce them to half the thickness of their central part, and so that the extremefends of one block are in a different plane to the extreme ends ofthe other block, as shown in Fig. 11. In this way blocks of longer length can be used than would otherwise be practicable. The end of the casing which receives the disk H is made in two parts, to enable the disk H to be put into place between them. Y

In the modification shown at Figs. 8 and 4 no casing A is used, but the guide-blocks L and the pins which carry them are on the inside of one end of the casing A. The guides K are fixed directly to the piston, and the piston is made sufficiently thick to contain the return-crank C within it. The same letters of reference are marked on the parts of these figures as in Figs. l and 2.

In the modification shown at Figs. 5 and 6 the construction is the same as shown at Figs. l and 2, except that the tubular neck at the end of the piston, which passes through the disk H, has upon it an internal toothed wheel, O,which gears with a fixed toothed wheel, P, carried by the interior of the end of the easing A', this toothed wheel being concentric with the crank-axis. It is not essential that the wheels O and I? should be toothed. They might be plain untoothed wheels.

In the modification shown at Fig. 7 the pump or engine is made double-that is, two pumps or engines, such as shown at Figs. l, 3, or 5, are placed together, while the pistons B, instead of being made to fit at all times against a point, AX, of the casing, are made to fit at all times one against the other. The two pistons are also set, as shown, so that when one piston is parallel with the crank-arms which carry it, theother piston is at right angles thereto, so as to equalize the iiow of iuid through the pump or engine. The movement of each of the pistons may be controlled in either of the ways hereinbefore described.

Figs. l2 and 13 show each piston provided with guides K K, as in Fig. '1, and these re- 4ceive blocks L L, turning on stationary pins M M. The two sets of blocks, L L, are in different planes. j

Having thus described the nature of my invention and the manner of performing the same, I would remark that I am aware that it has before been proposed to construct engines or pumps with a piston carried by the pin of a crank revolved in a casing of a form approaching somewhat to a cardioidal form; but in this case the extremities of the side edges only of the piston were made to iit up to the curved interior of the casing. With such a construction the size of inlet and'outlet ports which could be used was of necessity extremely limited; but by making the extremity of the inward bend of the casing to fit to the sides of the piston-ports of large dimensions may be employed, as in this way a division is always formed between the two ports. Also, by making the casing with the curve bending inward at one point to make a heart-shaped gure, I am able to make the piston of much less width than would otherwise be practicable. 4

The improved means hereinbefore described for controlling the movement of the piston also enables the movement of the piston to be more efficiently controlled than heretofore.

I would further remark that my invention in no way relates to engines in which the piston has a sliding movement through the axis or revolving part which carries it. In my engine lthe piston has no other motion than ro- IOO IIO

tary about the crank-pin upon which it is g inlet-port, E, and outlet-port F, separated by the inward bend AX of the casing, such in- Ward bend being made to t to the piston, substantially as described.

2. The combination of a cardioidal casing, A, a crank-axis, D, and crank-pin C, revolved therein, a piston, B, mounted upon the crankpin, a tubular neck, B', projecting from one end of the piston and carried through a disk, H, which isconcentric with the crank-axis, and is capable of revolving in an aperture in the end of the casing, and mechanism situated outside this disk for causing the piston B to make one-half a revolution for each revolution of the crank-shaft.

3. The combination of a cardioidal casing, A, a crank-axis, D, and crank-pin C, revolved therein, a piston, B, mounted upon the crankpin, pairs of guidebars K, carried by the piston, and blocks L, received between the guidebars, and capable of turning on pins M, to 2o control the movement of the piston, substantially as described.

4. The combination of a cardioidal casing, A, a crank axis, D, and crank-pin C, revolved therein, a piston, B, mounted upon the crankpin, pairs of guide-bars K, carried by the piston-blocks L,\received between the guidebars, and capable of turning on iixed pinsM, a bar, N, carried by one or both pins M, and an arm, C, on the end of the crank-pin C, carrying a 3o pin concentric with the crank-axis, which pin is received into a bearing in the bar N, substantially as described.

EDVIN BRYAN DONKIN. Vitnesses: l QT- WTT, I

G. W. WEsTLEY.

Both of 17 GmccchurchStreet, London. 

